Gents
I am not sure but it seems that MSFS is rebuilding each time kind of libray/layer and it is en endless startup time if you have many add-ons, first I think the process should be manual like it was with library in fax or P3dbut also maybe we could have a tool in dev mode or startup that give I dictation of the loading time needed by add-ons since sometime it freeze and I realize it could be link with poorly optimized add-ons like photograpetric ship traffic and so on
What do you think any idea work around
Load less stuff or make a cup of tea 
We need a log file like “that other” FS has. Why we haven’t gotten one three years in is beyond me. Just a simple log process so you can do your own troubleshooting, or ask others to help. Other than that, Baracus250 is right. You either load less stuff or kick back and relax. If it’s consistent, just load sections of your addons at a time and see which one causes problems.
Main impact on load times to main menu
- installed 1000s of liveries
- installed FSLTL, AIG, … models, every Aircraft/Livery combination is one aircraft addon (>1500 own aircraft.cfg files) that needs parsing time
f.e. for me (my system) with all sceneries i have active in community folder the load time without FSLTL is same as the extra load time for FSLTL aircraft. The size of scenery doesn’t effect load time to menu.
You can look at task manager during loading to menu and most time you see just cpu activity, but very low disk activity